Filter press



March 5, 1968 J. D. FANN 3,371,786

FILTER PRESS Filed Feb. 1, 1965 Y55 s3 54 QD-f J/ Mv@ 44 y F45 k W l"'ZU- James Fan/7 INVENTOR.

United States Patent O 3,371,786 FILTER PRESS .lames D. Faun, 3202Argonne, Houston, Tex. 77006 Filed Feb. 1, 1965, Ser. No. 429,397 -6Claims. (Cl. ZIO-90) ABSTRACT OF THE DISCLOSURE The disclosure is offiltration apparatus having pressure differential generating systemswherein both the filtration driving pressure and the back pressure arecontrolled. The back pressure is always maintained lower than thefiltration driving pressure, and the back pressure is controlled againstbecoming excessive, so that the filtrate receiver assembly is protectedagainst being subjected to excessive pressures.

Various liquids containing suspended solids, such as drill muds used inoil and gas well boreholes, are tested by filtration to predict theirbehavior characteristics under operating conditions. In the testing ofdrill muds, for example, filtration is preferably conducted underdifierential pressure conditions to simulate as closely as possiblepressure conditions in a borehole where the fluid may be used. Onemethod employed to remove solids from a liquid under differentialpressure conditions involves placing a test specimen of the liquid in acontainer which is provided with a filter medium. The filter mediumcornrnunicates with a filtrate line through which a liquid after removalof solids may be discharged 4from the container. A pressure source isconnected through an adjustable constant pressure discharge regulator tothe container for generating a head pressure on the liquid, a headpressure being a pressure which tends to force the liquid containingsuspended solids through the filter medium. A second pressure source isconnected through a second adjustable constant pressure dischargeregulator to the filtrate discharge line for creating a back pressure onthe liquid, a back pressure being one which tends to oppose movement ofthe liquid through the filter medium. Frequently, however, in thetesting of a liquid containing suspended solids, a back pressure will beapplied to the liquid which is greater than the head pressure due tomaladjustment of the back pressure regulator, causing the liquid to bedischarged out of the container into the head pressure regulator.Discharge of liquid into a head pressure regulator can both render the`regulator inoperable and cause data from tests being run to beinaccurate.

Additionally, receptacles for receiving filtrate from the container aregenerally subject to the back pressure of the apparatus and glass orplastic level gauges generally employed with these receptacles can beshattered due to maladjustments of the back pressure resulting ininjuries to operating personnel.

Typical prior art apparatus for testing of various materials areillustrated by the following United States Letters Patent:

F. B. Lomax, 2,089,702, Aug. 10, 1937; E. M. Brunner et al., 2,437,935,Mar. 16, 1948; P. L. Boucher et al., 2,599,742, June 10, 1952; M. B.Standing et al., 2,646,678, June 28, 1953; H. L. Twining, 2,733,595,Feb. 7, 1956; K. T. Norell, 2,909,286, Oct. 20, 1959; I. P. Gallus,3,055,208, Sept. 25, 1962; H. H. Ferrell et al., 3,139,747, July 7,1964.

The apparatus here-in disclosed has the ability to automaticallymaintain a constant back pressure. In some other systems, ltratecollects in the Iback pressure system causing the back pressure toincrease due to presence of the extra fluid. The excess pressuregenerated is usually hee relieved manually which requires that anoperator be present at all times during the test to relieve the excessback pressure as it builds up.

Accordingly, it is an object of this invention to provide an apparatusfor filtering of liquid containing suspended solids which eliminates thepossibility of back pressure on the liquid exceeding the head pressure.

Yet another object is to provide an improved means for sealing thefiltering medium in thel liquid container.

Still another object is to provide apparatus capable of -automaticallyrelieving excess 4back pressure.

The invention may be described generally as an apparatus for removingsolids from a liquid under differential pressure, which apparatusincludes container means for containing the liquid under pressure, meansfor filtering solids from the liquid and means for introducingcompressed gas into the container means for generating a head pressureon the liquid, which apparatus additionally includes the improvementcomprising; first means serving to communicate gas generating headpressure on the liquid with the filtration means for generating a backpressure on the liquid; and second means associated with the first meansfor maintaining a lower back pressure than head pressure on the liquid.

To be more specific, reference is now made to the drawings.

In the drawings:

FIGURE 1 is a schematic illustration of one emb0diment of the invention,

FIGURE 2 is a partial cutaway cross-sectional view of the liquidcontainer of FIG. 1 illustrating the filter medium retaining means,

FIGURE 3 is an enlarged partial cutaway crosssectional View oi theneedle valve illustrated in FIG. 2..

`Referring now particularly to FIGS. 1 and 2, cylindrical containermeans 1 is provided for containing a duid, such as a drill mud or thelike, which has suspended solids. Container `1 is preferably formed of ametal, such as stainless steel, which is capable of withstandingpressures on the order of 1000 pounds per square inch. Container 1 isprovided proximate its lower end with an annular recess 2 whichterminates at annular shoulder 3. Recess 2 is adapted to receive cupmember 4 which has a circular peripheral configuration. Cup member 4 isprovided with a circular lip 5 which defines a recess adapted to receivea filter medium 6 which is comprised of filter paper 7 which overliesA aperforate screen material 8. Obviously, other type filter media may beutilized. Above cups 4, Wall 59 of container 1 defines a chamber 9 forcontaining a test specimen of a liquid to be filtered.

To sealingly retain a liquid within container 1, a resilient seal meansis provided such as a Quad-Ring 11 which, as illustrated, resemples afour-leaf clover in cross-section. An O-ring or the like may be used,but a Quad-Ring is preferred. Quad-Ring 11 overlies the periphery offilter medium 6 and engages both lip 5 and shoulder 3l which, asillustrated particularly by FIG. 2, proximately abut. T0 assure sealingengagement of Quad-Ring 11 with shoulder 3 and lip S, cup member 4 iscompressingly retained within recess 2 by means of a beveled Cring 12.C-ring 12 is accommodated in an annular groove 13 provided in Wall 59 ofcontainer 1. Annular groove v13 forms a surface inclined radiallyoutwardly toward the shoulder portion of lrecess 2 to permit C-ring 12to compressingly retain cup 4 in recess 2 upon insertion of C-ring 12 ingroove 13.

`Cup 4 is provided with a passageway 14 which cornmunicates at itsupward end with the recess formed by lip S and at its lowermost end withan opening 15 defined by nipple 16.` Threadably engaged with nipple 16through threads 17 is a needle valve 18 provided with a conical tip 19.

The conical tip 19 upon full engagement of needle valve 18 with nipple16 engages passageway 14 as illustrated in FIG. 3 to block fluidcommunication therethrough. Rotation of needle valve 18 to move valve 18downward as viewed in FIG. 3 will permit communication betweenpassageway 14 and passageways 21 which converge into a passageway 22. Toprevent the leakage of fluid contained in chamber 15 around threads 17,an O-ring 23 is carried within groove 24 in needle valve 18 forsealingly engaging needle valve 18 with the interior Wall 25 of nipple16.

Referring back to FIG. 1, means are provided for establishing adifferential pressure across fluid in container 1. These means include apressure source such as the cartridge of pressurized gas 26 whichcommunicates through conduit 27 with the inlet port 28 of a conventionaladjustable constant pressure discharge regulator 29. Regulator 29 isadapted to reduce pressure applied to its inlet port 28 and apply thereduced pressure to its discharge port 31. Regulator 29 communicatesthrough conduit 32 with chamber 9 of container 1 for applying a headpressure to any liquid contained therein. Conduit 32 is provided with acoupling 30 of conventional design to permit removal of regulator 29from container 1. Discharge port 31 of regulator 29 also communicatesthrough conduit 33, needle valve 34 and conduit 35 with the port 36 of aconventional adjustable constant pressure discharge regulator 37Regulator 37 is provided with another port 38 which through conduit 39communicates with a filtrate receiver 41 which is preferably formed of ametal, such as stainless steel, capable of sustaining pressures on theorder of 1000 pounds per square inch (p.s.i.).

Filtrate receiver 41 is provided with conduit means 42 Whichcommunicates at its bottom end with the bottom of filtrate receiver 41and at its uppermost end with needle valve 18 which is schematicallyillustrated in FIG. l. Any suitable type of coupling can be used toconnect needle valve 18 and conduit 42. Needle valve 18, as explainedbefore, communicates through cup 4 and filter medium 6 with cham-ber 9of container 1. Conduit means 42 communicates through conduit 43, needlevalve 44 and conduit 45 with the exterior of filtrate receiver 41.Conduit 45 conveniently terminates in a graduated cylinder 46.

To permit gauging of pressures applied through discharge port 31 ofregulator 29, a conventional pressure gauge 47 is provided whichcommunicates with discharge port 31 through a conduit 48. Similarly,pressure applied through port 38 of regulator 37 may be sensed throughuse of a conventional pressure gauge 49 which communicates with port 38through conduit 51. Regulator 37 is preferably provided withconventional means for relieving pressure at its port 38 when thepressure at port 38 exceeds a predetermined pressure. Gas generating theexcess pressure at port 38 is relieved to the atmosphere through aconduit 52 which terminates in a bubble trap 53 which is filled with aliquid 54 such as water and vented to the atmosphere through an openingS5.

Means are also provided for raising the temperature of the test specimenabove atmospheric temperature. These means conveniently take the form ofa conventional thermostat controlled power source 56 which drives aheating element 57 disposed about container 1. Visual perception oftemperature in container 1 is permitted by use of a conventionalthermometer 58 which is carried within a recess (not illustrated) withinwall 59 of container 1.

In operation, container 1 is filled with a test specimen of a liquidcontaining suspended solids such as a drill mud by disconnectingcouplings 30 and 40, removing and inverting container 1, removingbeveled C-ring 12, cup 4, filtermedium 6 and Quad-Ring 11. A cap (notillustrated) may be placed over coupling 30 to prevent flowtherethrough, and then container 1 is filled with a test specimen ofliquid. After filling of chamber 9 with the liquid, the Quad-Ring 11,filter medium 6 and cup 4 are inserted in recess 2 as illustrated inFIG. 2. C-ring 12 is then radially compressed, placed in recess 2 andpermitted to expand J into groove 13 as illustrated in FIG. 2 forcompressingly retaining cup 4 in recess 2. Valve 18 is fully engaged toblock passageway 14 and prevent loss of fluid through passageway 14 whencontainer 1 is again inverted and placed in the position illustrated inFIG. 1. After removal of the cap (not illustrated) the couplings 30 and40 are connected. Valves 34 and 44 are closed to prevent communicationtherethrough as are regulators 29 and 37. Gas cartridge 26 is thenpunctured, releasing gas to inlet port 28 of valve regulator 29.Regulator 29 is then adjusted to apply a relatively small head pressureto liquid in container 1, for example, pounds per square inch, to assurethat cup 4 has been properly inserted and no fluid leakage will occurabout Quad-Ring 11. The temperature of the liquid is then brought to apredetermined level by operation of thermostat controlled power source56. Regulator 29 is then adjusted to apply a predetermined head pressureon liquid in container 1, for example 1000 p.s.i. The amount of pressurebeing applied can of course be determined by viewing of gauge 47.

Valve 34 is then opened permitting communication of regulator 37 withthe discharge port 31 of regulator 29. Regulator 37 is then adjusted toa predetermined pressure level, for example 200 p.s.i., which will bereflected by gauge 49. Valve 18 is opened permitting the pressureapplied at port 38 of regulator 37 to apply a 'back pressure throughpassageway 14 on the liquid in container 1. When the desired backpressure is reached, valve 34 is closed. Since the head pressure will begreater than the applied back pressure, liquid in container 1 will liowthrough filter medium 6, depositing solids thereon, and the filteredliquid or filtrate will pass through passageway 14 and into filtratereceiver 41 through conduit 42. As filtrate receiver 41 begins to fill,the back pressure on the liquid in container 1 will increase above thepredetermined discharge pressure of regulator 37 due to the confinementof gas creating back pressure. Regulator 37 through the relief meansprovided therein will relieve this excess pressure into bubble trap S3to maintain a constant back pressure. An indication of amount of`filtrate being retained in liltrate retainer 41 can be gained byobserving the amount of gas flow through bubble trap 53.

When a desired ltration period has elapsed, valve 18 is closed and valve44 opened to permit pressure in filtrate retainer 41 to force filtratecontained in the receiver 41 through conduit 43, valve 44 and conduit 45into graduated cylinder 46 where the volume of filtrate can be measured.

If, at the end of a test it becomes necessary or desirable to removeregulator 29 from container 1 before cooling of the test specimen iscompleted, valve means, (not shown) may be provided between regulator 29and container 1 to close communication therebetween yafter filtration ofa liquid is completed. By closing these valve means before reduction ofhead pressure, the pressure in container 1 can be maintained duringcooling of liquid therein to prevent boiling of the liquid which mayoccur if head pressure is reduced before the liquid cools.

Because both the head pressure applied to the fiuid in container 1 andthe back pressure applied through passageway 14 are derived from thedischarge port of regulator 29, the possibility of back pressureexceeding head pressure is eliminated. Thus, possibility of damage tothe head pressure regulator due to discharge of liquid outof container 1is eliminated. Additionally, only one pressure generating source isnecessary to create a differential pressure across a test specimen ofliquid. Because an operator can with reasonable accuracy determineamount of filtrate being collected by viewing bubble trap 53, no glassor plastic level gauges are needed and danger to operators fromshattered glass or plastic is eliminated. Additionally, because thefiltrate receiver can be constructed entirely of metal, the size of thecontainer to hold a given volume of liquid can be be reduced since glassordinarily employed to contain routine pressure is of necessity quitethick.

Gas cartridge 26 which may contain carbon dioxide, nitrogen or the likemay be any conventional type such as those manufactured by Walter KiddeCompany. Regulator 29 may conveniently be a series 1100 regulator soldby Air Reduction Company, and regulator 37, including relief means, maybe a type 16-003 manufactured by the C. A. Norgren Company. Pressuregauges 47 and 49 may be of any conventional type such as those sold byAir Reduction Company. While -rather specific terms have been used todescribe one embodiment of the invention, they are not intended norshould they be construed to limit the scope of the invention as definedby the appended claims.

What is claimed is:

1. In apparatus for removing solids from a liquid under differentialpressure, which apparatus includes container means for containing theliquid under pressure at one part thereof having means thereacross forfiltering solids from the liquid and a filtrate discharge line fromanother part thereof at the opposite side of said filtering means fromsaid one part, the improvement comprising:

a gas cartridge adapted to discharge pressurized gas;

a first adjustable constant pressure discharge regulator having an inletport which communicates with the cartridge and a discharge port whichcommunicates with said one part of said container for applying apredetermined head pressure on a liquid contained therein;

a second adjustable constant pressure discharge regulator having a firstport which communicates with the discharge port of the first regulatorand a second Port;

the second regulator including means for relieving pressure to theatmosphere when pressure at its second port exceeds a predeterminedpressure and also being adapted to maintain a predetermined pressure atits second port which is lower than the pressure impressed upon itsfirst port; first valve means interposed between the first and secondregulators; for opening and closing communication therebetween;

a uid tight filtrate receiver which is in communication with the secondport of the second regulator;

Ifirst conduit means communicating the bottom of the filtrate receiverwith the filtrate discharge line;

second valve means interposed between the filtrate discharge line andthe first conduit means for opening and closing communicationtherebetween;

second conduit means communicating the first conduit means With theexterior of the filtrate container for removing filtrate therefrom;

third valve means interposed in the second conduit means for opening andclosing communication therethrough; and

gauge means in communication with the discharge ports of the first andsecond regulators for indicating pressure at the respective ports.

2. A filtration apparatus for removing solids from a mixture thereofwith liquid under differential pressure,

comprising a chamber having thereacross a filter means for receivingsaid mixture on one side of said filter means, a fluid tight filtratereceiver, means communicating said receiver with said chamber on theother side of said filter means, pressuring means connected to saidchamber for establishing a head pressure on said mixture on said oneside, means for maintaining a predetermined back pressure in saidreceiver and on said other side below said head pressure by the amountof said pressure differential, comprising first conduit means extendingbetween said chamber and said receiver, valve regulator means in saidfirst conduit means controlling said back pressure, means associatedwith said valve regulator means to prevent the back pressure fromexceeding a predetermined amount.

3. The combination of claim 2, said pressuring means comprising pressurecylinder means containing a supply of fluid under pressure and secondconduit means extending from said pressure cylinder means to aconnection with said rst conduit means between said chamber and saidvalved redgulator means, said second conduit means including pressureregulator means whereby pressured fluid delivered from said pressurecylinder means to said first conduit means and to said chamber iscontrolled at substantially constant pressure.

4. The combination of claim 3, said first conduit means including valvemeans disposed in said first conduit means between said connection ofsaid second Conduit means to said first conduit means and said valvedregulator means, pressure measurement means communicating with saidfirst conduit means between said valved regulator means and saidreceiver means, and pressure measurement means communicating with saidfirst conduit means adjacent its said connection to said chamber.

5. The combination of claim 4, including valve third conduit meansextending from the filtrate outlet of said filter means to saidreceiver, said first conduit means being releasably coupled to saidchamber and said third conduit means being releasably coupled to saidreceiver means, whereby said chamber and filter means may be removed forcleaning and filling.

6. The combination of claim 5, said receiver means being a steelpressure vessel having valved fourth conduit means for conductingfiltrate flow from the bottom thereof to the Aexterior thereof, saidthird conduit means being flow connected to said fourth conduit meanswithin said receiver means whereby filtrate introduced into saidreceiver means through said third conduit means is introduced into thebottom of said receiver means, said first conduit means connection tosaid receiver means being to the top of said receiver means.

References Cited UNITED STATES PATENTS 2,539,355 1/1951 Reichertz 73-382,737,804 3/1956 Herzog et al 73--38 3,139,747 7/1964 Ferrell et all37-566 X SAMIH N. ZAHARNA, Primary Examiner.

